Linear polyester compositions containing a gentisic acid derivative as a heat stabilizer



United States Patent LINEAR POLYESTER COMPOSITIONS CONTAIN- ING A GENTISIC ACID DERIVATIVE AS A HEAT STABILIZER Gerald R. Lappin and Louis D. Moore, Jr., Kingsport,

Tenn., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application September 21, 1956 Serial No. 611,371

4 Claims. (Cl. 260-453) This invention relates to the heat stabilization of synthetic linear polyesters of high molecular weight. Linear polyesters are extensively used in textile fibers, which are subject to heating in the processes of washing, drying at elevated temperatures, ironing and pressing. Linear polyesters are also used in films and shaped articles which are subjected to heating in their various uses, such as in electrical insulation and the like. Heating tends to degrade linear polyesters, as has been discussed by H. A. Pohl in Journal of the American Chemical Society 73, 5660-5661 (1951), and by I. Marshall and A. Todd in Transactions of the Faraday Society 49, 67-78 (1953).

When polyesters are heated at elevated temperatures, they degrade in physical properties and in molecular weight as measured by the logarithmic viscosity number, {7 defined by the equation where 1 and 1 are the viscosities respectively of pure solvent and of a solution containing C grams of polymer per 100 cc. of solvent. The logarithmic viscosity numbers reported herein were measured in a 60:40 mixture by weight of phenolztetrachloroethane at a polymer concentration of about 0.23 gram/100 cc.

In the course of our investigation of the thermal breakdown of linear polyesters, we have found that the addition of certain compounds to the polyesters retards thermal degradation. The mechanism of this protection is not completely understood, but it has been shown that oxygen has a detrimental effect; therefore, the compounds may be functioning as antioxidants. However, we have found that a great many antioxidants are not stabilizers for linear polyesters.

We have found that linear polyesters can be heat stabilized by the incorporation of a small proportion of a gentisic acid derivative selected from the group consisting of gentishydrazide,

2,835,648 Patented May, 20, 1958 ice 0H and gentisanilide,

I OH

The gentisic acid derivative can be incorporated into the resin either by mixing it into the molten resin, which may then be extruded or molded, or by adding it to a solution or dope of the resin, which may then be cast as a film or spun as a filament. Concentrations of from 0.1 to 10 parts by weight of gentisic acid derivative per parts by weight of linear polyester may be used; we prefer to use from 0.3 to 3 parts per 100 parts of polyester.

The effectiveness of the stabilizer was tested by placing film strips or tensile specimens of the polyester containing the stabilizer in a 200 C. air oven for a given length of time. The values of {1;} and/or of tensile strength were determined before and after the heating. A comparison of these figures with those obtained on a blank of the same batch of polyester provided a measure of the stabilizing eiiect of the additive.

In the examples given below, gentishydrazide was incorporated in the indicated proportions with several different batches of a linear polyester designated as 3:2:5 C:S:B, made from a 3 :2:5 mole ratio of azelaic acid:4,4- dicarooxyphenyl sulfone,

HOOCC H .SO .C H COOH: 1,4-butanediol with a linear polyester designated as 5:1:6-SzTzN, made from a 5:126 mole ratio of 4,4-dicarboxyphenyl sulfonezterephthalic acidzneopentyl glycol; and with a linear polyester designated as 3:2:5-TzBzH, made from a 3:225 mole ratio of terephthalic acid:sebacic acidzcyclohexane- 1,4-dirnethanol. Cyclohexane-l,4-dimethanol has the formula HOCH .C H .CH .OH

Gentisanilide was incorporated in the indicated proportions with the linear polyester designated as 3:2:5- CzSzB, described above.

Parts Gentlslc Acid Derivative per 100 Polyester Parts Polyester Original After 15 hrs.

1 Genttshydrazlde... None 1 Gentishydrazide... None lqGentlshydrazlde None S 1 Gentlshydrazlde... None Sa e 1 Gentlshydrazlde one 1 Gentisanillde.. None S Tensile Strength (in p. s. 1.)

Elongation,

percent Original 15 hrs.

Original 15 hrs.

8 {1 Gentlshydmzlde None What we claim as our invention and desire to be secured by Letters Patent of the United States is:

1. A linear polyester composition comprising a linear polyester stabilized against degradation by heat by a content of from 0.1 to 10 parts by weight of a gentisic acid derivative selected from the group consisting of gentishydrazide and gentisanilide per 100 parts by Weight of polyester.

2. A linear polyester composition comprising a linear polyester stabilized against degradation by heat by a content of from 0.3 to 3 parts by weight of a gentisic acid derivative selected from the group consisting of No references cited. 

1. A LINEAR POLYESTER COMPOSITION COMPRISING A LINEAR POLYESTER STABILIZED AGAINST DEGRADATION BY HEAT BY A CONTENT OF FROM 0.1 TO 10 PARTS BY WEIGHT OF A GENTISTIC ACID DERIVATIVE SELECTED FROM THE GROUP CONSISTING OF GENTISHYDRAZIDE AND GENTISANILIDE PER 100 PARTS BY WEIGHT OF 